Tapered roller bearings on railcar axles support operating loads capable of producing deflections in the axle, and in particular, the end portion of the axle comprising the journal on which the tapered roller bearing is affixed. The stresses imposed by the operating loads are particularly high in the journal portion of the shaft at or near the backing ring.
As result of shaft deflections, the backing ring and the journal often experience fretting wear as the backing ring moves relative to the journal. Fretting wear may be sufficient to loosen the backing ring, increasing the axial play of the bearing on the journal. The loose backing ring accelerates wear on the bearing assembly and journal, potentially leading to shaft or bearing failure.
Through use of a bearing seal, the bearing attempts to retain lubricants in the form of oils or grease while also excluding external water and abrasives. The bearing seal is a ring shaped structure that usually includes a resilient seal member.